Lin Yi, a university student, often buys braised pork intestines at the night market. He discovers that Auntie Zhao, who runs an old stall, has long been overcharging regular customers. Meanwhile, a couple who have come from elsewhere use fresh ingredients, offer honest service, and charge fair prices, yet struggle to attract customers. Determined to stand up for what is right, Lin Yi agrees with the couple on four principles of honest business and helps them attract customers through campus social groups. Their suddenly booming stall makes Auntie Zhao resentful, and she launches a series of malicious reports, undercuts their prices, and creates all kinds of obstacles. Armed with complete evidence and legal knowledge, Lin Yi calmly resolves each crisis. In the end, the couple's small stall, built on integrity, successfully becomes a popular shop, while Auntie Zhao suffers the consequences of her own schemes, proving that only honest business practices can ensure lasting success.